A medical drug delivery device such as for instance an insulin injection device or an insulin pump for substantially continuous delivery of insulin, or any other medical liquid drug delivery device need a high security level to ensure that the correct dose size or volume flow of liquid drug is delivered to the user, and that there is at all delivered drug to the user. A potential error in a liquid drug delivery device is an occlusion anywhere in the outlet path from the drug container to the delivery point such as the tissue or a vein of a user. For instance an injection needle mounted in fluid connection to a drug cartridge through a penetrable septum can be occluded, or a butterfly needle luer lock connected to a liquid drug container can be occluded. Another problem is the occurrence of a leak in the drug container itself or along the fluid drug delivery line. A security system is therefore needed to sense if an occlusion or a leak occurs in the medical drug delivery device so the appropriate action can be taken, such as change of needle and recalculation of an appropriate dose. U.S. Pat. No. 7,195,609 addresses the problem of detecting an occlusion or a leak by incorporating a sensor in the movable piston of a product container and connecting the sensor via wires for monitoring the pressure in the drug container. However U.S. Pat. No. 7,195,609 poses the problem of connecting the sensor via wires which are complicated and expensive to manufacture and mount and poses a security problem as the wires can be broken or the electrical connections can be poor or corrode.
The amount of drug delivered is important, but further the correct type of drug is crucial and poses a security issue in medical drug delivery devices. This problem is discussed in WO 9965548, which discloses a way to share information on syringe configuration between syringes and injector systems.
Thus, there is a need for a simple and cost effective system to ensure correct dose size, reliability of dose delivery and correct type of drug delivered from a medical liquid drug delivery.